Science (English Medium) Class 12 - CBSE Question Bank Solutions for Chemistry

For the metallurgical process of which of the ores calcined ore can be reduced by carbon?

(i) Haematite

(ii) Calamine

(iii) Iron pyrites

(iv) Sphalerite

Wrought iron is the purest form of iron. Write a reaction used for the preparation of wrought iron from cast iron. How can the impurities of sulphur, silicon and phosphorus be removed from cast iron?

How is copper extracted from low grade copper ores?

The purest form of iron is prepared by oxidising impurities from cast iron in a reverberatory furnace. Which iron ore is used to line the furnace? Explain by giving reaction.

The mixture of compounds A and B is passed through a column of \[\ce{Al2O3}\] by using alcohol as eluant. Compound A is eluted in preference to compound B. Which of the compounds A or B, is more readily adsorbed on the column?

Why is sulphide ore of copper heated in a furnace after mixing with silica?

Write down the reactions taking place in Blast furnace related to the metallurgy of iron in the temperature range 500-800 K.

Explain the following:

\[\ce{CO2}\] is a better reducing agent below 710 K whereas \[\ce{CO}\] is a better reducing agent above 710 K.

Explain the following:

Generally sulphide ores are converted into oxides before reduction.

Explain the following:

Silica is added to the sulphide ore of copper in the reverberatory furnace.

Explain the following:

Carbon and hydrogen are not used as reducing agents at high temperatures.

PH₃ forms bubbles when passed slowly in water but NH₃ dissolves. Explain why?

SF₆ is known but SCl₆ is not. Why?

On reaction with \[\ce{Cl2}\], phosphorus forms two types of halides ‘A’ and ‘B’. Halide A is yellowish-white powder but halide ‘B’ is colourless oily liquid. Identify A and B and write the formulas of their hydrolysis products.

White phosphorus reacts with chlorine and the product hydrolyses in the presence of water. Calculate the mass of \[\ce{HCl}\] obtained by the hydrolysis of the product formed by the reaction of 62 g of white phosphorus with chlorine in the presence of water.

Using valence bond theory, explain the following in relation to the complexes given below:

\[\ce{[Mn(CN)6]^{3-}}\]

(i) Type of hybridisation.
(ii) Inner or outer orbital complex.
(iii) Magnetic behaviour.
(iv) Spin only magnetic moment value.

Using valence bond theory, explain the following in relation to the complexes given below:

\[\ce{[Co(NH3)6]^{3+}}\]

(i) Type of hybridisation.
(ii) Inner or outer orbital complex.
(iii) Magnetic behaviour.
(iv) Spin only magnetic moment value.

Using valence bond theory, explain the following in relation to the complexes given below:

\[\ce{[Cr(H2O)6]^{3+}}\]

(i) Type of hybridisation.
(ii) Inner or outer orbital complex.
(iii) Magnetic behaviour.
(iv) Spin only magnetic moment value.

Using valence bond theory, explain the following in relation to the complexes given below:

\[\ce{[FeCl6]^{4-}}\]

(i) Type of hybridisation.
(ii) Inner or outer orbital complex.
(iii) Magnetic behaviour.
(iv) Spin only magnetic moment value.

Mark the correct order of decreasing acid strength of the following compounds.

(a)
(b)
(c)
(d)
(e)